A general discussion on starting issues...
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Cargo Master
Joined: Jul 2009
Posts: 2,541
Likes: 54
From: Des Moines
A general discussion on starting issues...
I'm not having a particular problem, but I was giving a guy a jump start today and the way his motor was turning over got me thinking about "why does that happen?"
I ended up spending about 10 minutes with him, letting my trusty F150
charge up his battery while we waited patiently. In that time, he tried 5 times to start it, and each time the motor would initially crank, getting maybe 1/2-3/4 of a turn, but then just stop.
So I was wondering- what causes that to happen? In this case, the guy's battery was shot, but it doesn't make sense to me to have a live feed from a jump and have this still happen.
So is it compression that halts a motor mid-crank, meaning that the battery just doesn't have the amperage to overcome the compression? Is it weak electrical connections and/or bad cables? A combination of these things?
Just curious, and thought a group discussion would make it all better.
I ended up spending about 10 minutes with him, letting my trusty F150
charge up his battery while we waited patiently. In that time, he tried 5 times to start it, and each time the motor would initially crank, getting maybe 1/2-3/4 of a turn, but then just stop.So I was wondering- what causes that to happen? In this case, the guy's battery was shot, but it doesn't make sense to me to have a live feed from a jump and have this still happen.
So is it compression that halts a motor mid-crank, meaning that the battery just doesn't have the amperage to overcome the compression? Is it weak electrical connections and/or bad cables? A combination of these things?
Just curious, and thought a group discussion would make it all better.
Elder User
Joined: Mar 2013
Posts: 559
Likes: 0
From: In Hastings Delton area
A number of things can cause cranking and starting problems ;weak bad battery loose dirty battery or starter cables bad starter or battery ground .Or a bad starter meaning its got worn bushings or the brushes are worn or bad causing the starter to pull high amps and the starter to turn over slow or not at all.
Senior User
Joined: Nov 2011
Posts: 456
Likes: 1
From: Owensboro, KY
When you jump start one, the bad battery is a big load as well. By that I mean, (and the way I do it, which is wrong but quick) next time opportunity knocks, remove the negative terminal on the bad battery, the vehicle to be jumped will start right up! Assuming you have a good connection with the jumpers anyway. Without wasting much time, reconnect the negative and let the alternator charge it.
Yes, it is bad for the alternator, I wouldn't recommend doing it regularly, but if you're in a pinch and pressed for time, it is quick.
Yes, it is bad for the alternator, I wouldn't recommend doing it regularly, but if you're in a pinch and pressed for time, it is quick.
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
Yeah I've had it where a dead battery prevented jump starting. We were just bs'in here at work last week about how newer batteries don't even give you much warning before they fail. Older ones seemed to crap out slowly, where it would steadily provide less and less current to the starter before failing completely. The newer ones are fine one day, dead the next.
OP, yes when you have questionable electrical connections and a weak battery, combined with the compression of the engine, it usually results in the starter not having enough power to turn the engine over. If you have a high compression engine, sometimes the compression alone can give the starter a hard time, which is why there are high-torque, gear reduction starters available.
OP, yes when you have questionable electrical connections and a weak battery, combined with the compression of the engine, it usually results in the starter not having enough power to turn the engine over. If you have a high compression engine, sometimes the compression alone can give the starter a hard time, which is why there are high-torque, gear reduction starters available.
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